Conversion of hydrocarbons



1944; v. A. KALI CHEVSKY 2, 4

' v CONVERSION 6F HYDROCARBONS Filed Jun 12, 1942 Patented FebQlS, 1944 CONVERSION OF HYDRO(351M501?!Sv Vladimir a. Kalichevsky, Woodbury, N. .L, assignor to Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application June 12, 1942, Serial No. 446,701

1 Claim.

This invention has to do with the conversion of hydrocarbons, is interested in theconversion of hydrocarbons in the presence of a contact mass, and has specifically to do with methods whereby hydrocarbons of greater than gasoline-boiling oil boiling range, 1. e., hydrocarbons boiling between about 400 F. and 700 F. or somewhat more, may be heated to temperatures of about 800 to 900 F. and at those temperatures, in vapor phase, may be subjected to conversion in the presence of contact mass material such as, for example, those comprising an association of alumina and silica to yield high percentages of gasoline. Such processes are quite well disclosed in various patents, particularly those to Eugene Houdry and associates. It is also well known that whenthe vapors, leaving the catalyst case in such types of reaction are subjected to fractionation, they may be separated into .two parts, one being the gasoline product and lighter constituents, and the other beinga gas oil material of about the same character as that originally charged except that it may be more refractory to catalytic cracking.

It is also known that in thermal hydrocarbon conversion processes, such unconverted material I fractionated from the products of conversion may be recycled to the originalconversion processes for ultimate utilization therein.

This invention is directed to a method for the proper retreatment and ultimate conversion to products of material unconverted in a single stage of a vapor phase catalytic treatment. It has for its object the provision of a sequence of method steps whereby a proper degree of ultimate conversion of the material originally fed as charge may be had.

This invention may be understood readily by reference to the drawing attached to this specification, the single figure of which shows in h ghly diagrammatic form the process Of the disclosure as clothed in appropriate apparatus. In the drawing a charge stock of the nature of gas oil maybe introduced through pipe I and forced by pump 2 through furnace 3 tom discharged through separator 4, from which any material not 'vaporous at the cracking temperature may be discharged from the system through cooler 5. The vaporous charge stock heated to a temperature appropriate for reaction flows through pipe 6. In the case of a stock of a low end point, the separator 4 may be dispensed with, the oil vapors being directed by proper valving through pipe i.' The conversion operation occurs in a catalyst case 8 between the ends of which there is placed a bed of contact mass 9. Heated vapors are introduced to the contact mass through manifold l0, leading into a series of pipes H which extend into the catalyst bed 9 ,and are equipped with orifices l2. Vapors are removed from the contact mass by a similar series of pipes l3, carrying orifices M and leading into manifold l5, all in a manner well-known in the art.

Converted vapors are led from manifold l5 into fractionator It, there to be separated into an overhead product withdrawn through pipe ll, cooled in l8, collected in IQ and removed from the system through 20, a portion being returned for fractionator control by pump 2|, and a hottoms product removed through 22. This bottoms product is a material of gas oil nature having physical characteristics quite like that of the original charge stock except that it may be more refractory toward vapor phase cracking in the presence of a contact mass. It is also to be noted that in fractionator I6, I may, if desired, withdraw a portion of the material heavier than the desired gasoline-like product through pipe 23, and if I do not desire to treat all of the fractionator bottoms, ma withdraw some through pipe 24.

Material to be retreated or recracked is led through pipe 25 and forced by pump 26 through furnace 21 and into separator 28, for the separation, if desired, of a heavy out which may be withdrawn from the system through 29'. Vapors,

at'reaction temperature, pass from separator 28 through pipe 29 to contact with a contact mass in reaction casefll which is exactlythe same in detailas reaction case 8, vapors entering case 30 through manifold M and being removed throughmanifold 32. In case the material to be recracked is not of too high an end point it may be directed through pipe- 33 by suitable valving without usingseparator 28. Reacted vapors through manifold 32 may be disposed of either through pipe 34 where they are led into the inlet manifold of reaction case 8, orthey may be led by pipe 35 directly to fractionator It to be treated in company with reacted vapors from case 8.

It is of course to be understood that in the reaction cases shown which are equipped with contact mass beds in situ, that regeneration of the contact mass is needed from time to time and consequently alternate reaction cases and regeneration means not herein shown are provided so that the treating may continue while spent reaction cases are being regenerated, all as known and common in theart.

With the arrangements shown in the drawing, several methods of operation may be utilized. For example, gas oil may be converted upon its first pass through case 8 at a temperature of approximately 850 F. to produce in fractionator l6 something like 40% by vol. of gasoline and lighter material and somewhat over 50% by vol. of a fraotionator bottoms, also of gas oil nature, insofar as regards boiling point. This gas oil may then be heated to a similar or a higher temperature and passed through reaction case 30 there to be similarly converted. The arrangements shown permit of several variations. The conversion in the second case of the recycled stock may be conducted at an increased temperature, other conditions being the same as in the first pass, it may be treated with a catalyst of different activity or, all other conditions being the same, it may be handled at different space velocities. All of these are merely means of setting up within the second catalyst case those special conditions of operation, particularly suitable for the stock being fed thereinto, as distinguished from the fresh charging stock being fed to the first case. The vapors from the second reaction case may be passed directly to fractionator Hi. It is preferred, however, that instead of passing these vapors through pipe 35,

they should be fed through pipe 34 and passed through reaction case 8 in company with the virgin stock charged thereto. This gives rather decided advantages in that in this manner the material to be recracked can be given a longer exposure to contact mass, while at'the same time, the virgin stock may be given a lesser exposure and thus, the cracking capabilities of the two stocks may be so paired off together as to realize the most effective conversion from both. In this fashion there is an advantage arising from the concurrent presence of the cracked, recycled material from reactor 30 in reactor 8 at the same time as virgin material which results in a lesser deposit of coke upon the contact mass in 8 for the same conversion of virgin material therein than would be the case were the virgin material present therein alone. I

Similarly, while providing capabilities f0] separate treatment of virgin and recycle stocks it will be noted that the system herein described is so set up as to permit the discarding from the system of a heavy portion of recycle particularly at 24 and more preferably at 29 whereby the capabilities of reaction balance within the system may be most fully utilized and a highly complete utilization of the stools originally fed to the system may be made.

The invention above-described has been explained in terms of the conversion of hydrocarbons of higher boiling point to gasoline. It has also been explained in terms of bed-in-place contact masses which are to be regenerated in situ. It is to be understood that the description in these terms is by way of example only and that the invention is not to be restricted thereto or thereby except insofar as restrictions are expressed in the following claims. The process is useful for other conversions for hydrocarbons, such as, for example, the polymerization of gaseous hydrocarbons to materials of high-boiling point, the catalytic reforming of naphthas, and other operations. The reaction zones may be occupied by flowing contact masses, moving either concurrently or countercurrently to the material being treated. All such and their equivalents are deemed by me to be within the scope of my disclosure when used in the method defined in the following claim.

I claim:'

A method for the conversion of hydrocarbons in the presence of a contact mass comprising subjecting vaporous hydrocarbons at a conversion temperature to contact with a contact mass catalytic to the desired conversion, separating the hydrocarbons from the contact mass, fractionating them into a converted portion and an unconverted portion, revaporizing the unconverted portion and subjecting it to contact with a second contact mass and then passing it in contact with the first contact mass in company with the fresh.- feed to be further converted therein, and to be fractionated therewith, whereby the unconverted material from the fractionator is subjected to conversion conditions different from those applied to the fresh feed.

VLADIMIR A. KALICHEVSKY. 

